London — Jack Guntrip pauses for a moment, trying to find the right words to summarize the man that is Usain Bolt. Why is Bolt the single most exciting athlete at the London 2012 Olympics? It is an important question, the blond-haired and befreckled young boy knows, and he wants to make sure he makes his feelings plain.

Bolt will run Thursday night in the 200 meters, his favorite event. If he wins, he will become the first Olympian ever to win the 100 and 200 meters at consecutive Olympics – an achievement, he says, that is the last step toward him becoming "a legend."

Michael Phelps might have more medals here, the better work ethic, and the cleaner and more Olympic lifestyle, but he doesn't have it. At least, not by the measure of the hometown crowd. Phelps is respected here, certainly, but Bolt is beloved.

While Phelps is a steely efficient medal machine – somewhat indulgently allowing himself his contented smile here in London – Bolt is a traveling carnival of irrepressible exuberance. When he runs, the crowd is not an adjunct to his performance, but the fuel for it. He is there not just to run fast – which he does, and breathtakingly – but to run fast for them, and they know it.

He is the fastest show on spikes, and for many of those at London 2012, the most enjoyable act in the Olympics' five-ring circus.

"The razz-a-matazz gets the crowd excited," says Ollie Golden, who is at the Olympic Stadium to watch track and field. "He just transcends sport."

For many Britons, track and field is the main event at the Olympics and swimming is the clear undercard. When the US track and field team went to Birmingham, England, for a pre-Olympic camp, the people "treated us like rock stars," said American high jumper Jesse Williams at a press conference.

And Bolt is the best in the world at track's blue-ribbon event. "There is something about the 100-meter sprint that is iconic," says Robert Fox, who has come to the Olympic Stadium with his brother and father. "It's the gold standard."

Not too long ago, the same was true in the US. Think back to 1988. Was America buzzing more about sprinter Carl Lewis or swimmer Matt Biondi? Biondi, who won five gold medals at the Seoul Games was respected, certainly, but Lewis was beloved.

And this is a measure of Phelps's impact on the American Olympic landscape. He has flipped the Olympic calendar. Now, the first week of the Olympics is America's "gold standard," and track has become a second act.

For the rest of the world, though, the image of eight men sprinting down the track at speeds that cars find only in third gear is still one of the most awesome in all sport. "He's the fastest man on the planet," says Gus Guntrip, Jack's father, simply.

And then there's the Swedish handball team.

After winning the 100 meters, Bolt said he would celebrate by taking it easy and getting some sleep that night. The 200 meters was still ahead, after all. That night, though, he posted a picture of himself with three members of the Swedish women's handball team, amid media reports that he celebrated with them for 1-1/2 hours.

He's also repeatedly insisted that he wants to get a tryout for Manchester United, England's most successful soccer team during the past two decades.

"There's an air of unpredictability about Usain Bolt," says Ian Cooper, a teenager watching the track and field with this family.

One minute he's false starting at the world championships and losing to compatriot Yohan Blake in the Olympic trials and being written off as out of shape and unfocused, the next he's winning the 100 meters in Olympic-record time and playfully yelling to Blake after the race that the upcoming 200 is his "pet race," and "I'm not going to let him win."

At the post-race press conference, he makes faces at the press, he explains his pre-race antics in great detail, he asks the press not to be too judgmental because there were vegetables in the McDonald's chicken wrap he ate for lunch, so "it was healthy."

If the Olympic athletes were to produce a yearbook, Bolt would be "Athlete Most Likely to Pull a Practical Joke on the Moderator."